The present invention is generally related to phototypesetting and more particularly to an improved photocomposition machine which is convenient to operate in an error-free manner and with a minimum amount of operator training.
Over the years, many photocomposition machines have been proposed or manufactured. The earliest tmachines were an adaptation of the hot metal line casting, in which the metal casting was replaced by individual photographic character elements. Later machines used photomechanical and electronic methods to select, expose, and space the characters on a photographic film or paper. Some of these machines took the form of manual typewriters with permutation bars to generate width codes for the various characters via a mechanical memory coupled to control circuitry and counters. In these machines, the photographic unit included a continuously rotating disk, flash lamp and stepping film carriage for leading. These earlier systems in which the keyboard interfaced directly with the machine, required the skilled operators to compose copy in justified lines.
With the introduction of computer technology, machines were later introduced which provided justification by way of computer controller. Highly complex machines were developed which could accommodate input from several operators. Such machines also have the capability of handling several thousand characters per second and providing automatic hyphenation and line justification. Typically with such machines, the operator types on the keyboard which develops a punched tape which is read and the information therefrom stored in a memory for appropriate processing under the control of a computer program.
While these sophisticated machines provide many automatic functions, they are very costly to manufacture and still require considerable training to operate. Thus, the total cost of installing such photocomposition machines is often beyond the financial means of the smaller printing operations.